Next Gen 2011: Hollywood's Fastest-Rising Stars

There's a reason Rosenberg, 34, chose to focus on music once he decided to pursue a career in entertainment law. "I was a shitty piano player and a shittier singer," he cracks. "But I knew I wanted to be among creative professionals and around music." Growing up in Kansas City, Mo., Rosenberg immersed himself in Motown and R&B, and then carried his love for the genre through seven years at Harvard (where he attended undergrad and law school). It would help him land an internship at Arista Records, a clerkship at Greenberg Traurig and then his first major client, John Legend, in 2002. Today, as his firm's youngest partner ever, he represents some of the biggest names in music, including Jennifer Lopez, Justin Bieber and songwriter Diane Warren. He has also made a concerted effort to recruit top executives as clients, including Lady Gaga manager Troy Carter. Says Rosenberg: "It takes a certain type of person to bring the needs of commerce and art together. It's a talent not a lot of executives have, and the ones that do, they're rock stars, too. Think about it: How do you get in a room and tell Lauryn Hill that her nine-minute song needs to be down to three?" Rosenberg credits his negotiating skills to being the middle of three brothers and the indispensable advice of his mom and mentor: Never take no for an answer. "She got her Ph.D. in chutzpah, which she most certainly passed on to me."